Research on Short Circuit Current Calculation of Distributed Power Grid with Asymmetric Faults

In order to reduce the calculation error of short-circuit current in power grids with distributed power sources, a method for calculating short-circuit current in power grids with distributed power sources under asymmetric faults is proposed. Clarify the three types of short-circuit current sources for distributed power generation: system power supply, motor type, and converter type. Simplify the converter type DG with a voltage controlled current source model and unify the expression of voltage sources. Based on the equivalent topology of faults, the symmetrical component method is used to decompose the power grid into a sequence component network, and the calculation is carried out step by step: first calculate the sequence voltages of each node, then construct boundary equations according to the fault type, and finally solve the short-circuit current and node voltage and convert them into three-phase values, achieving efficient and accurate calculation. The experimental results show that compared with the simulation results, the method proposed in this paper has high calculation accuracy under two types of asymmetric faults, with errors basically controlled within 2 %. It can accurately simulate short-circuit currents and adapt to distributed power access scenarios.